Heavily refactor code:

  * Separate the policy decisions into a derived class [InlineSimple]
  * Move the inlining mechanics into a base class [Inliner]
  * Change the inliner to be an SCCPass, making it more structured and
    eventually pipelinable with other SCC passes

llvm-svn: 8257

1 files changed, 119 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/IPO/Inliner.cpp b/llvm/lib/Transforms/IPO/Inliner.cpp
new file mode 100644
index 00000000000..7f75f1453fc
--- /dev/null
+++ b/llvm/lib/Transforms/IPO/Inliner.cpp
@@ -0,0 +1,119 @@
+//===- InlineCommon.cpp - Code common to all inliners ---------------------===//
+//
+// This file implements the code shared between the LLVM inliners.  This
+// implements all of the boring mechanics of the bottom-up inlining.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Inliner.h"
+#include "llvm/Module.h"
+#include "llvm/iOther.h"
+#include "llvm/iTerminators.h"
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "Support/CommandLine.h"
+#include "Support/Debug.h"
+#include "Support/Statistic.h"
+
+namespace {
+  Statistic<> NumInlined("inline", "Number of functions inlined");
+  Statistic<> NumDeleted("inline", "Number of functions deleted because all callers found");
+  cl::opt<unsigned>             // FIXME: 200 is VERY conservative
+  InlineLimit("inline-threshold", cl::Hidden, cl::init(200),
+              cl::desc("Control the amount of inlining to perform (default = 200)"));
+}
+
+Inliner::Inliner() : InlineThreshold(InlineLimit) {}
+
+int Inliner::getRecursiveInlineCost(CallSite CS) {
+  return getInlineCost(CS);
+}
+
+bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) {
+  CallGraph &CG = getAnalysis<CallGraph>();
+
+  std::set<Function*> SCCFunctions;
+  DEBUG(std::cerr << "Inliner visiting SCC:");
+  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
+    SCCFunctions.insert(SCC[i]->getFunction());
+    DEBUG(std::cerr << " " << (SCC[i]->getFunction() ?
+              SCC[i]->getFunction()->getName() : "INDIRECTNODE"));
+  }
+  DEBUG(std::cerr << "\n");
+
+  bool Changed = false;
+  for (std::set<Function*>::iterator SCCI = SCCFunctions.begin(),
+         E = SCCFunctions.end(); SCCI != E; ++SCCI) {
+    Function *F = *SCCI;
+    if (F == 0 || F->isExternal()) continue;
+    DEBUG(std::cerr << "  Inspecting function: " << F->getName() << "\n");
+
+    for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
+      for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
+        bool ShouldInc = true;
+        // Found a call or invoke instruction?
+        if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
+          CallSite CS = CallSite::get(I);
+          if (Function *Callee = CS.getCalledFunction())
+            if (!Callee->isExternal()) {
+              // Determine whether this is a function IN the SCC...
+              bool inSCC = SCCFunctions.count(Callee);
+
+              // If the policy determines that we should inline this function,
+              // try to do so...
+              int InlineCost = inSCC ? getRecursiveInlineCost(CS) :
+                                       getInlineCost(CS);
+              if (InlineCost < (int)InlineThreshold) {
+                DEBUG(std::cerr << "    Inlining: cost=" << InlineCost
+                                << ", Call: " << *CS.getInstruction());
+
+                // Save an iterator to the instruction before the call if it
+                // exists, otherwise get an iterator at the end of the
+                // block... because the call will be destroyed.
+                //
+                BasicBlock::iterator SI;
+                if (I != BB->begin()) {
+                  SI = I; --SI;           // Instruction before the call...
+                } else {
+                  SI = BB->end();
+                }
+                
+                if (performInlining(CS, SCCFunctions)) {
+                  // Move to instruction before the call...
+                  I = (SI == BB->end()) ? BB->begin() : SI;
+                  ShouldInc = false; // Don't increment iterator until next time
+                  Changed = true;
+                }
+              }
+            }
+        }
+        if (ShouldInc) ++I;
+      }
+  }
+  return Changed;
+}
+
+bool Inliner::performInlining(CallSite CS, std::set<Function*> &SCC) {
+  Function *Callee = CS.getCalledFunction();
+  Function *Caller = CS.getInstruction()->getParent()->getParent();
+
+  // Attempt to inline the function...
+  if (!InlineFunction(CS)) return false;
+  ++NumInlined;
+              
+  // If we inlined the last possible call site to the function,
+  // delete the function body now.
+  if (Callee->use_empty() && Callee != Caller &&
+      (Callee->hasInternalLinkage() || Callee->hasLinkOnceLinkage())) {
+    DEBUG(std::cerr << "    -> Deleting dead function: "
+                    << Callee->getName() << "\n");
+    std::set<Function*>::iterator I = SCC.find(Callee);
+    if (I != SCC.end())       // Remove function from this SCC...
+      SCC.erase(I);
+
+    Callee->getParent()->getFunctionList().erase(Callee);
+    ++NumDeleted;
+  }
+  return true; 
+}